Printing telegraph radial switching system



May 3, 1932.

G. A. LOCKE PRINTING TELEGRAPH RADIAL swITcHING SYSTEM 3 Sheets-Sheet lFiled Aug. 13, 1930 /A/l/ENTO/P G.A.LOCKE B Mw u AT ORNEV 1930 .'5Sheets-Sheet 2 G. A. LOCKE PRINTING TEIIEGRAPH RADIAL swITcHING SYSTEMFiled Aug.' 13,

May 3, 1932.

A TTORNEV /M/ENTOR GA .LOC/(E EINQJIIIHII.

III'IIIIII May 3, 1932- l G. A. LocKE 1,856,714

FRINTING TELEGRAPH RADIAL SWITCHING SYSTEM A FiledAug. 1s, 1930 73sheets-sheet s VTT" .n

sur/olv l T RECEIVING 4 REPEA TER nrcan/vc sur/0N SEND/N6 I RECEIVING 62'PRINTER /N VEA/70H @Amc/f5 MAW A TTOR/VEV Acapable of broadcasting to aPatented May 3, 1932 UNITED STATES PATENT OFFICE GEORGE A. LOCKE, OFGLENWOOD, NEW YORK, .ASSIGNOR T0 BELL TELEPHONE LABO- RATORIES,INCORPORATED, OF NEW YORK, N. Y., A CORPORATION Ol' NEW YORK PRINTINGTELEGRAPH RADIAL BWITCHING SYSTEM rlhis invention relates to printingtelegraph switching systems and more particularly to a system which hasa central station plurality of other stations.-

This application relates to improvements in or modifications of thesystem disclosed in the. U. S. application for patent of Perry SerialNo. 462,890 filed June 21, 1930.

A primary object of. this invention is to` produce a printing telegraphtypewriter system whereby an instrument at one of several switchboardsmay send a message which will be received and recorded in typewrittenform on a selected few or on all machines connected to the system.

Another object is to provide means for controlling the apparatus at allswitchboards in the system from a remote central switchboard and forvisually indicating to the operator at the central switchboard theproper functioning of the apparatus at each otice.

A feature of this invention is a special rotary switch circuitarrangement located at each otlice for conditioning the apparatus toautomatically rebroadcast messages to a group of stations.

A further feature is the use of circuit means'whereby the centralswitchboard may obtain control of each local switchboard.

Tn general` the switching system to be dcscribed comprises a centralswitchboardconnected to several distant local switchboards. Each ofthese. in turn, is connected through branch circuits with the variouslocal receiving stations of which it forms the central point. Telegraphchannels are utilized to connect the central switchboard with all thelocal switchboards. These channels may be used singly or simultaneouslyand over them it is possible to carry on a two-way simultaneous (duplex)service.

system of this type is especially adapted tor use in police Work and inbusiness concerns where it is necessary quickly to send information tomany distant localities simultaneously. The operator at the machinesimply types the message on a keyboard similar to that of a standardtypewriter and what is typed is automatically recorded on vthe receivingmachines. -In this manner a permanent record is made by both thetransmitting and receiving machines.

In the accompanying drawings Fig. l shows diagrammatically, the generalarrangement of a radial printin telegraph system embodying the featureso this invention;

Fig. 2 shows in detail the circuit diagram of the central switchboard orgeneral headquarters of the system; and

Fig. 3 shows in detail the circuit diagram of the local or divisionheadquarters.

General features of the system Fig. 1 serves to enable the reader toquickly comprehend the manner in which the various circuit diagrams, tobe explained later, are connected with the system as a whole.

The telegraph system shown in F ig. 1 cornprises a central or generalheadquarters station A and two division stations B and C. Each stationis equipped with a switchboard `1 having, normally associated therewitha.

printing telegraph transmitting and receiving set 2. From each stationtelegraph lines 3 eX- tend to receiving only sets 6. A one-way polarrepeating station 4 is provided for each telegraph line 3. Two-waytelegraph channels 8 connect each division station with the centralstation A. These channels may be either full duplex or two one-waychannels over which two-way simultaneous servicemay be carried on. Ateach station a receiving set 9 individual to each telegraph channel 8 isprovided. Repeaters may be inserted in these channels if desired. Therepeaters may be full duplex, one-way or any of the repeaters commonlyused and well known in the telegraph art for two-Way simultaneouscommunication.

The repeater 4 may be located at the switchboard or at a specialrepeater board located near the station. v At central station A aspecial remote control code or selector key 7 is provided fortransmitting a series of code impulses for conditioningthe apparatus ateach division station for automatically rebroadcasting mes'- with eachdivision.

sages received over the telegraph channels 8.

Although only two division stations are shown in Fig. 1, as manydivision stations may be provided as are considered desirable ornecessary for a particular telegraph switching system. Several receivingsets 6 may be arranged in series with any particular telegraph line 3.

In general, the operation of selector key 7 at general headquarters willactuate the relay equipment at all the. division headquarters to whichthe central station desires to broadcast. This relay equipment willretransmit the incoming signals to all the receiving sets connectedtothe switchboard of which it forms the central point. At the salnetime, general headquarters may broadcast the signals to the receivingsets connected to its own station if it so desires. The switchboard atstation A is so arranged that by means of keys it may transmit to aselected few or all division stations connected to the system. Itgeneral headquarters wishes to communicate with any or all divisionheadquarters without broadcasting to the receiving stations associatedwith the respective division switchboards this may be done bytransmitting from general headquarters without operating code selectorkey 7.

In addition, receiving sets 9 are provided at the central switchboard Aand at the respective division switchboards for connection in eachtelegraph channel 8 associated In broadcasting from central station Aeach of the sets 9 located at A is actuated by the proper functioning ofthe apparatus at the respective division station to which the set isconnected by its respective telegraph channel 8. In this manner,headquarters is provided with a visual typewritten record of the messagebeing broadcast and automatically retransmitted back over the telegraphchannel 8 as an indication of the proper functioning of the apparatus ateach oiice. l

The detailed operation of the system will now be explained in connectionwith Figs. 2 and 3.

Broadcasting from general headquarters Fig. 2 taken together with Fig. 3and placed to the left of Fig. 3 shows a schematic circuit of thegeneral headquarters station equipment as well as that of a divisionstation equipment. In connection with these figures, the circuitoperation will irst be considered for broadcasting a message fromgeneral headquarters (Fig. 2) to one or more division stations (Fig. 3).Only two telegraph channels and two receiving stations are shownconnected to the central switchboard.

Assuming that the operator at general headquarters desires to broadcasta message through -the division headquarters to the receiving stationsassociated with the divisions,

code selector key 7 will be operated. The operation of code key 7through one revolution will transmit a series of tive special break andmake signals by causing spring 11 of the key to make and break contactwith the metal of the key thus opening and closing the operating pathfor relay 12. Relay 12 is a special master relay with two windings andis normally held operated to its marking position on a circuit frombattery through the upper winding of relay 12 to ground through thesending and receiving printer 13 and the contact of code key 7 Currentthrough the lower or biasing winding tends to operate relay 12 againstits spacing contact. The strength of the current flowing through theupper winding is greater than the biasing current and holds the armatureof relay 12 to its marking contact. The transmission of an open or breaksignal from printer 13 or code key 7 will open the operating circuitthrough vthe upper winding and cause. the armature of relay 12 to moveto its spacing contact.

At this point it will be noted that sending relays 14, 15, 16 and 17have their operating windings connected in series in a circuit havingone end connected to the spacing contact and the other end connected tothe marking contact of the master relay 12, as shown. Resistances 40 and41 connect the marking and spacing contacts, respectively, of. relay 12to battery 18. The armature of relay 12 is grounded.

As the armature ot relay 12 operates in accordance with signalstransmitted from printer 13 or from code selector key 7, it causes thespacing and marking contacts of relay 12 to be grounded alternately.With the armature thereof on the spacing contact, current Hows frombattery 18 through resistance 40 through the windings of all the sendingrelays in series and thence to ground through the spacing contact andarmature of relay 12. All the sending relays 14, 15, 16 and 17 are thenoperated against their respective spacing contacts. When the armature ofrelay 12 moves to its marking contact, the direction of current flowthrough the windings of the sending relay is reversed, flowing nowthrough resistance 41 and through the windings of the sending relays inseries ,to ground through the marking contact and armature of relay 12.The sending relays are thus operated against their respective markingcontacts. In this way all the sending relays are caused to followsignals transmitted from printer 13, simultaneously. Any number ofsending relays may be inserted in the circuit with their windings inseries to transmit signals to any desired number of division stations orbrancll receiving stations.

The operation of sending relay 14, in accordance with the signalstransmitted by rer ...is

repeaters D and D lay 12, will open and close a circuit traced frompositive battery 43 through the winding of relay 20, contacts of relay14, through one side of telegraph channel 18 through the receivingprinter 48, one Winding of relay 46, break contact of relay 50 to ground47 at the division headquarters (Fig. 3), thus operating the receivingprinter and causin the armature of relay 46 to move to its mar inposition. The operation of relay 46 (F1g. 3) will actuate relayequipment at the division switchboard connected to channel 18 and causesignals to be automatically transmitted back over the line to operatereceiving print-v er 26. This will be described in connection with Fig.3. As mentioned previously, full duplex, one-way and other repeaters maybe inserted into the telegraph channel it considered desirable.

Relay 20, in releasing, will light lamp 22 as an indication to theoperator at the switchboard that signals are being sent to the divisionstation connected to telegraph channel 18.

Key 24 is provided for short-circuiting the contacts of sending relay 14to prevent the signals from being transmitted over channel 18. In thismanner the central switchboard may broadcast to a selected few of thedivision stations or to all the divisions as desired. l

It is to be noted that the operator at gen eral headquarters, bywatching the lamp indicators or the position of keys 24 and 25, canquickly observe which division stations are connected to receive thebroadcast signals. The operation of the receiving set 26 is a visualindication to the central switchboard that the apparatus at the divisionstation to which the set is connected is functioning properly.

Receiving set 26 is also used to receive signals transmitted from thedivision switchboard. This will be described in connection with thetransmission of signals from a. division station.

Telegraph channel 19 connects another division switchboard to thecentral switchboard. Lamp indicator 23 and receiving set 27 associatedwith sending relay 15 and telegraph channel 19 are provided to functionin a manner similar to that described for lamp indicator 22 andreceiving set 26 associated with sending relay 14. Short-circuiting keyand relay 21 are connected in the circuit in a manner similar to thatdescribed for short-circuiting key'24 and relay 20 and serve a similarpurpose.

For operating the branch receiving sets 31 and 32, which are local tothe central switchboard. sending relays 16 and 17 and keys 37 and 38 areprovided. One-way polar connect the central switchboard with thereceiving sets through telegraph lines 33 and 34. The polar repeatersare well known in the telegraph art and their operation Will bedescribed in connection with the transmission of signals to thereceiving stations.

To Vcondition repeater D for transmitting, key 37 is operated. This willremove shortcircuiting ground 30 from the marking contact of' relay 16and permit the operation of sending relay 16, in accordance with theoperation of master relay 12, to correspondingly operate relay on acircuit from ground on the armature and contactof relay 16 to batterythrough the left winding of relay 35. Relay 35 has two windings, throughone of which a biasing current flows. This biasing current normallytends to keep the armature against the left Contact. The low of currentthrough the lett winding operates relay 35 and causes its armature tomove to the right. The alternate movement of the armature of relay 35will transmit current tirst of one polarity and then of the otherlpolarity to operate receiving set 31 over telegraph line 33. Filter 39is a noise killer and servesto reduce undesirable interference in othertelegraph wires.

In a similar manner, receiving set 32 will receive the transmittedmessage through oneway polar repeater D` identical with D) and uponoperation of key 38.

At this point, it will be noted that in cases where the receivingstation is not at a great distance from the switchboard the one-way ypolar repeater may be eliminated. In such case battery will be suppliedat the contact of -`relay 16 instead of ground,v and key 37 will beinserted in series with the telegraph line 33 with ground 30 removedfrom the circuit.

It will ybe noted that the operator at the central switchboard maytransmit to one or all divisions, and to one or all the receiving setsconnected to general headquarters by operatingthe proper keys. This isquite different from the division switchboard which will now bedescribed.

Receiving broadcasting signals at drision headquarters Returning to thecondition previously described Wherein sending relay 14 operated. itlwill be recalled that the operation of relay 14 operated relay 46 to itsmarking position and also operatedreceiving printer-48 (Fig. 3).Normally the armature of relay 46 is held to its marking contact over acircuit traced from l ground 47 (Fig. 3) make contact of relay 50through the right-hand winding of relay 46, receiving printer 48,telegraph channel 18 to battery 43 (Fig. 2). It will be noted that asmall amount of current flows through the left or biasing Winding ofrelay 46. This current tends to move the armature of relay 46 to itsspacing contact but is not of suiiicient strength to overcome thecurrent through the right or operating winding.

The operation of code key 7 will cause spring 11 to momentarily breakcontact w-ith the metal wheel of'key 7 which, in turn, will cause theoperation of relay 12 and sending relays 14, 15, 16 and 17 to theirrespective spacing contacts. The operation of relay 14 to its spacingcontact `will open the operating path through the right-hand Winding ofrelay 46 which will now move to its spacing contact. The movement of thearmature of relay 46 to its spacing Contact will complete a circuit tooperate relay 49 on a path from ground on the armature and spacingcontact of relay 46 to battery through the winding of ielay 49. At thispoint it will be noted that relay 51 is normally operated on a circuitfrom ground on the armature and marking contact of relay 46 to batterythrough the winding of relay 51. Therefore, the operation of relay 46will cause the release of relay 51. The release of relay 51.Willcomplete a circuit to operate rotating magnet 52 on a path from groundon the armature of relay 51 to battery through the winding of magnet 52,operating magnet 52 and advancing selector switch 53 one step. Theadvance of the selector switch will automatically close the ofi' normalcontacts ON, thus preparing a circuit for the later operation of releasemagnet 54. This will be described subsequently. Relays 49 and 51 aredesigned to be slow in releasing so as not to follow the printerVsignals. At this time springll of code key 7 will have again madecontact with the key to reoperate relay 12 and move the armature ofrelay 12 to the marking contact. -.This will operate sending relay 14(Fig. 2) to its marking contact, in turn, operating relay 46 to itsmarking contact.

The operation of relay 46 to its marking contact will reoperate relay 51and open the operating path for relay 49 which will not release at thistime smce the special signal sent by code key- 7 is of too short aduration to permit slow release relay 49 to fall back. When spring 511of code key 7 again leaves the metal projection of the key to transmitanotherbreak signal, selector switch 53 will be advanced another step ina manner similar to that hereinbefore described. When selector switch 53reaches step #5, after code key 7 has revolved one revolution thustransmitting five special break signals, a path will be completed tooperate relay from ground on the brush arm of 53 through the windings ofrelays 50 and 60 to battery 55 operating relays 50 and 60. Relay 50, inoperating, will light lamps 70 on a circuit traced from grould on theright armature and make contact of relay 50 through lamps 7 0 to battery55. Relay 56 will also operate on a circuit from ground on the leftarmature and make contact of relay 50 to battery through the windprinter13 at headquarters.

ing ofrelay 56, thus transferring the oper- Y ating path of relay 63from printer 62 to This last circuit is traced from battery 43 (Fig. 2),marking Contact of relay 14, telegraph channel 18, -receiving printer48, one winding of lrelay 46, right make contact of relay 56, upperwinding of relay 63, let make contact of relay 56 to ground. Masterrelay 63 is thus put under control of printer 13.

At this point it will be noted that when code key 7 returns to itsnormal position after rotating for one revolution, relay 49 will releaseand relay 51 will reoperate. Selector 53 will stay on contact 5 until adisconnect signal is transmitted over the circuit. Relay 46 and masterrelay 63 will follow the printer signals. Master relay 63 operates toactuate individual sending relays 64, 65 and 66 in the same manner ashereinbefore described in connection with master relay 12 of Fig. 2. Theoperation of relay 60 will remove the short-circuiting ground of key 67from the contact of relay and permit relay 68 to follow the operationsof sending relay 65. The operation of the polar repeater set D from thesending relay is similar to that herein described in connection with theoperation of polar repeater D of Fig. 2. Incidentally, it will be notedthat the operation of relay 50 placed a ground on lamp indicators as anindication to the operator at the division station that generalheadquarters has taken control of the station for broadcasting.

Broadcasting from the central switchboard may now take place.

Receiving set 48 at the division switchboard will record the messagesreceived from the central board. Relay 46 and master relay 63 willfollow all signals. Relay 63 will automatically re-transmit all incomingsignals to the sending relays 64, 65 and 66. Relays 49 and 51 aredesigned to be slow in releasingand will not follow the message signalsactuating relay 46. Relay 64 will open ate in response to the. operationof relay 63 and will open and close a circuit traced from battery 45through `the Winding of relay 7 2, contact of relay 64. telegraphchannel 18, receiving printer 26 to ground 44. Receiving set 26 willrespond to these signals. In this manner the central board will receivethe retransmitted message from the division stations while broadcastingto the latter.

Relay 72 will light lamp 71 in accordance with the signalsretransmitted. in a manner heretofore described in connection with relay20 and lamp 22 in Fig. 2.

It will be apparent that there may be many more sending relays in serieswith relays 65 and 66 and. also, more line relays in series with linerelay 60` if the number of receiving stations desired Warrants theadditional apparatus.

It is to be noted that the central switchboard may seize control of thecircuit at any time and disconnect sending and receiving printer 62 fromthe master relay 63. lI lso, for broadcasting from the centralswitchboard to receiving sets local to the division switchboard. key 67,individual to each local branch receiving set, need not be thrown. Theoperation of relay servesthe purpose of conditioning the one-way polarrepeater for transmitting signals to the branch receiving sets.

After broadcasting a message, general headquarters may send a disconnectsignal i to restore the circuit to normal by again operating code key 7for one revolution or by transmitting a break signal.

If code key 7 is utilized for sending a disconnect signal, then the rstbreak signal transmitted, as spring 1l leaves key 7I` will release relay46 to its spacing contact. The release of relay 46 will operate relay 49and cause the release ot relay 5l. Rotating magnet 52 will then functionfrom ground on the armature and contact of relay 5l to battery throughthe winding of magnet 52. The brush arm of selector switch53 will beadvanced to step 6, thus opening the operating path for relays 50 and 60which will release.

Relay 50, in releasing, will cause the release of relay 56 and will openthe lighting circuit for lamps 70. When the brush arm of selector switch53 reaches the tenth step. code key 7 will be restored to normal; relay5l will be operated and relay 49 released. A circuit will then becompleted to restorevselector switch 53 to normal on a circuit tracedfrom ground on the brush arm thereof through the ott` normal contacts ONto battery through the winding of release magnet 54, operatingl magnet54 to restore rotary selector switch 53 to normal and to open off normalcontacts ON. The circuit at division headquarters will now have beenrestored to normal.

it a break signal is used for transmitting a disconnect signal then theopencircuit caused by the break signal will cause the brush arm toadvance one step to contact #6 as hereinbeiore described. lVhen thebreak signal is completed relay 46 will again operate to its markingcontact and relay 49 will release. A circuit will then be closed torestore selector 53 tonormal over a path traced from battery throughrelease magnet 54, break contacts of relay 49, oitn normal contacts ONto ground on contact 6 and brush arm of selector 53.

Sending from division switchboard If the division station desires totransmit to its own local branch receiving stations, sending printer 62is utilized. Relay 63 will be under the control of printer 62 and willfunction to actuate sending relays 64, 65 and 66 in the same manner asthat described in connection with receiving signals from generalheadquarters.

The operation of relay 64 will transmit the message back over telegraphchannel 18 by operating receiving printer 26 at the central switchboard.

In order to transmit to thev local receiving station 69, key 67 must bemanually operated. The operation of the key 67, removes ground on the.swinger of the key from the left winding of relay 68 and permits thelatter to follow the operations of 65. The operation of relay 68,inaccordance with the operation of sending relay 65, causes the signalsto be retransmitted to receiving set 69. It is to be understood that thecircuit description for transmitting to receiving .set 69 applies aswell to the operation of all other receiving sets connected to thedivision switchboard.

Although only one sending and receiving printer is shown at the centraland division switchboards, it is understood, of course, that othersending and receiving printers may be provided for use when a printerset becomes disabled.

What is claimed is:

l. A printing telegraph exchange system of the type used forbroadcasting messages from a central switchboard to a plurality ofremote switchboards, said remote switchboards in turn rebroadcastingsaid messages to a plurality of branch stations local to each board,characterized -in this that selector mechanism is utilized at the remoteswitchboards for conditioning apparatus at said` boards forrebroadcasting, said selector mechanism being responsive to code signalsfrom said central switchboard.

2. A switchboard for transmitting signals to a plurality of stationsincluding a rotary selector switch comprising a plurality of contacts, amagnet associated therewith, a brush arm, circuit means associated withone of said contacts, said magnet being responsive to signals forconnecting the brush arm of said selector switch with said circuit meansthrough said one contact, and relay means responsive to said connectionfor conditioning the switchboard for transmitting signals.

3. In combination a'rotary selector switch comprising a brush arm, agroup of contacts, a magnet for advancing said arm over said contacts,an additional magnet for advancing,

said arm to restore it to its normal position, a slow releasing relaynormally operated, and adapted to energize said first magnet to advancesaid brush arm upon the deenergization of said slow releasing relay,another slow releasing relay normally non-operated, and adapted toenergize said second magnet to restore said brush arm to normal, saidiirst and second relays being so arranged in a circuit that when oneslow releasing relay is Y arm to a normal position, said first magnet soperating its associated magnet the other slow releasing relay cannotfunction to operate the other magnet.

4. In combination a closed transmission circuit, a relay seriallyconnected in said circuit and responsive to impulses of currenttransmitted thereover, a slow releasing relay responsive to theenergization of said rst lrelay in one sense, a second slow releasingrelay responsive to the deenergization of said first relay in anothersense, a selector switch,

a group of contacts, a brush arm adapted 'to make contact with saidcontacts, a magnet for advancing said brush arm contact by) contact, asecond magnet for restoring the rush being under the exclusive controlof said first slow releasing relay and said second magnet being underthe control of said second slow acting relay.

In witness whereof, I hereunto subscribe my name this 30th day of July,1930.

GEORGE A. LOCKE.

